1. FIELD OF THE INVENTION
The present invention pertains to medical devices. The instant invention relates to medical devices implanted within the human body. The subject invention pertains to devices being implanted within the human body for purposes of draining cerebrospinal fluid during the treatment of hydrocephallus. Further, the present invention relates to improved devices for controlling the fluid flow when the pressure differential between an upstream and downstream area may become sufficiently large.
2. PRIOR ART
Devices for draining cerebrospinal fluid are know in the art. However, in some prior devices one way check valves alone are incorporated to promote drainage of the cerebrospinal fluid. Such valves fluidly communicate with the brain area and other parts of the body. However, rapid decreases in the pressure of the parts of the body to which the fluid is being drained may cause substantial fluid to be transported from the brain in a manner which is too rapid. Such a condition may have deleterious results and possibly cause death of the patient where such prior devices have been implanted.
In some prior drainage devices there has not been included a mechanism whereby the fluid flow may be terminated when the downstream pressure of the body to which the fluid is being drained becomes too low with respect to the upstream fluid pressure. Such prior device did not provide automatic flow control of the fluid being drained from the brain area.
The device of which this improved system is based, provided for adequate control of the passage of cerebrospinal fluid from the brain under a wide variety of conditions. However, in some cases, it was found that under particular pressure differential conditions there resulted a closure of the mechanism to terminate flow through the device and provided a condition where it was difficult to open the valve mechanism subsequent to the termination of fluid flow. This may have deleterious results in that once the valve mechanism is closed there may be some time lag within which the valve remains closed.